Governing mechanism for centrifugal compressors.



GOVERNING MECHANISM FOR GENTEIFUGAL OOMPRESSORE APPLIIOATION FILED DEC. 28, 1911.

1,076,882.; I Ptented 0'@t.21,1913.

Compressor IO Fig.1.

I Decrease In crease Speed p Qofn pressor Invenbon,

bH wa Richard Trgerj" RICHARD TRCGER, OF CHABLCTTENBURG, GERMANY, ASSIGNOB TO GENERAL ELECTRIC CGMPANY,

A GORPOR-ATIQN OF NEW.YQRK.

- GOVERNING- MECHANISM roe CENTRIFUGAL oolurrtnssons.

Specification of Letters Patent.

Patented Oct. 21,1913.

. Application filed December 28, 1911. Serial No. 668,340.

To 0 107mm 5? may concern:

lie it known that I, RICHARD Tatiana, a subject of the King of Prussia, residing at Clmrlottenburg, Germany, have invented certain new and useful Improvements in Governing Mechanism for Centrifugal Compressors, of which the following is a specification. I

Certain types of centrifugal compressors, with which I am familiar, have been provided with a relief or blow-off valve located in the dischazge'pipe that is intended to open when the work performed by the com pressor falls below a certain predetermined small value. The object of the valve .is to prevent surging or pumping, as it is commonly designated, of the fluid, undergoing compression. These blow-cit valves have been actuated either by means of a non-return valve located in the discharge pipe, or by a means which is responsive to, a pressure difference existing between two points in the discharge pipe. which pressure difference bears a definite relation to the work performed by the compressor. These devices are open to certain material disadvantages. which it is the purpose of my present invention. to overcome. In the first place the power available for operating the blowcfl valve is comparatively small and depends to a certain degree upon atmospheric conditions. In the second place, the friction of the moving parts of the blow-off valve and of its actuating means has to be taken into account; this being a more or less uncertain quantity which increases with the life of the apparatus by reason of impurities of one .kindror another that are deposited on the parts. Due to lack of power or to friction or bothjthe valve may even fail to operate. Theseyarious objections havercsulted inpractice in adjusting the blow-off valve so thatfli t opens before the ivork performed by the com ressor has been reduced to the lowest permissible value. That is to say, the parts are so set that the blow-off valve instead of opening just as the surging is about to take place opens While the load considerably above that value. In other words, with the arrangements heretofore used, the effective range of the compressor has been unduly reduced. Furthermore, owing to the unfavorable conditions existing between the actuating means and the blow-oil valve, the latter is caused to open spasmodically, thus giving rise to IIDPUlSGS or pulsations in the compressor, and also in the net WOrkof tubular passages connected thereto.

I avoid the difliculties' above mentioned first, by so arranging the-blow-oif valve that it is dependent as to its position upon the work performed by the compressor and' hence of the motor that drives it, and sec- 0nd, by positively actuatingsaid valve. By reason of my improved construction or arrangement, the blow-off valve will not be opened until the work performed by the compressor has been decreased to its smallest permissible value, and in this manner the efiective range of the compressor is increased. t

In the accompanying drawing which illustrates one of the embodiments of my invention, Figure 1 shows a centrifugal air compressor driven by an electric motor, and Fig. 2 is a modification wherein the blowoff valve of the discharge pipe is connected to a throttle valveii the inlet pipe.

1 is a rotary compressor of any suitable construction having an admission conduit 2 and a discharge conduit 3. Located in the discharge conduit is. a blow-off valve 4, which is actuated means of a two-part stem or rod 5, the upper end of the rod be ing connected to the valve, and the lower rnd to a projection on the'worm gear segment 6. By dividing the valve into two parts as shown, a 1051; motion connection is provided which permits the gear to move through a portion of its range Without disturbing the valve. The compressor is driven by an electric motor 7 of any suitable construction. As shown, 'it is driven by a shunt wound direct current machine.

8 and 9 indicate the mains supplying current to the motor. In circuit with thefield winding 10 of the motor "is aresistance 11 of suitable construction. Arranged to travel over the contact points connected to the resistance is an arm 12 that has attached to it a worm gear segment 13. Located beactuator tween the worm gear segments 6 and'13 is a. worm 14, the latter being rotated in one direction or the'other to change the resistance inthe fieldfcircuit by the hand wheel 15. As the load'on the compressor increases, the resistance is adjusted so that the speed of the motor will increase. Conversely, as the load on the compressor decreases, theresistance is adjusted to decrease the speed of the motor. Owing to the fact that the worm 14 meshes with the segments 6 and 13, it follows that. any movement of one causes a movement of the other. Under normal conditions, the blowofi valve 4 rests on its seat, and the lower part of the stem 5 moves up and down Without affecting it.. hen, however, the segment 6 is swung to the right, the lost motion between the'parts ot' the valve stem is first taken up and then the blow-oft valve is opened permitting compressed air or other fluid to escape from the discharge pipe 3. The opening of the valve 4 takes place only when the motor .10 is operating at nearly its lowest speed.

IVhen it is operating at higher speeds, the,

lower part of the valve stem 5 moves away from the upper part and the-pressure in the pipe 3 holds the valve against its seat.

In Fig. 2 the valve 4 is arranged as before and is actuated by a bell-crank lever 16, which in turn is operated by acrank 17 on the lower end of the stem 18 of a butterfly throttle valve 19. The upper end of its stem is provided with a pinion 20 that meshes with a gear 21, the latter being actuated by a pinion 22- that is on the shaft 23. lVhen the butterfly valve is moved to a position, where itnearly closes the inlet 2, the bellcrank lever 16 will begin to open the blowoff valve. This opening of the blow-off valve increases as the throttling efiect in the inlet pipe, due to the butterfly valve, is increased. Conversely, when the butterfly valve is opened it permits the blow-off valve 4 to seat and thereafter has no eifect. To state the matter in another way, a throttling valve is provided in the inlet and a blow-oft valve in the outlet, which valves are connected through a lost motion connection that. is so arranged that the valves may operate simultaneously under certain conditions, and separately under other conditions.

I have described and illustrated two forms of lost motion connections or devices between the stem of the blow-off valve and its actuator. but it is to be understood that any other device suitable for the purpose may be provided.

It will be evident from the description. and illustration that the blow-oil valve can be accurately adjusted to open just before the load has been reduced (either by cutting oil' consumption devices or other means), to that certain predetermined value where surging can take place. This means hat the cti'eetive range of the apparatus has been increased because the opening of the blow-olf valve has been delayed to the last moment, and because the delinite opening of the valve at the proper time has been assured.

Since the Work performed by the comprossor varies with that of the motor, and since there is a direct relation between the position of the regulator of the motor and that of the blow-ott valve, it follows that the latter is responsive to the amount of work performed by the compressor. In one aspect of my invention the driving motor and its regulator constitute a means for varying the output of the compressor, and since the position of the blow-off valve is determined directly'by the regulator and indirectly by the speed of the motor it follows that said means control the blow-off valve. Of course, without going outside the invention, the performance-regulating members oi. the compressor upon which the blowoti' valve is dependent, may be adjusted aulomatically in any way instead 01' by hand as shown. Automatic and hand operated members for controlling the. work performam'c of the compressor may he used in the same machine, in which case the blow-oli valve should be so anangcd as to be under the control of both of said members.

The electric motor shown may be talten as typical of any form of motor, and the regulator as typical of any form of regu lator suitable for the motor with which it is associated.

In accordance with the provisions of the patent statutes. I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that. the appa7atus shown is only illustrative, and that the invention can be :ai'ried out by other means.

Vhat I claim as new and desire to secure by Letters Patent of the. United States,is

1.. In combination, a centrifugal compressor which is subject to surging at light loads, a means for varying the output of the compressor, and a valve for regulating the amountof fluid delivered by the compressor which is actuated by the said means.

2. In combination, a centrifugal compressor which is subject to surging at light loads, a means for var; 'ing the output of the, conipressor, and a surge preventing valve. tha is located on the discharge side of the compr sor and is opened responsive to said means when-the hutput is reduced to such a small percentage of the total that surging would otherwise take place. I

3. In combination, a centrifugal compressor which is subject to surging at. light loads, a means for regulating the amount of wort: performed by the com pressor. a normally closed valve which when opened prevents the load on the com prcssor from falling below a prc lctermincd amount. and a lost, motion connection betwcmi said means and the valve which arranged to mow; the valve when the regulating means has decreased the out put o f the compressor to a point where surgmg would otherwise take lace.

4. In combination, a. ce trifugal compressor which is subject to surging at'light loads,

inlet and discharge conduits therefor, a

driving motor, a regulator for the motor,'a

normally closed valve in one of the conduits that is adapted to be opened to prevent the load on the compressor from falling below the point where surging takes place, and means that iscommon to the regulator and valve for moving the regulator and opening sor which is subject to surging at light loads,

inlet and discharge conduits .therefor, a driving motor, regulating mechanism for the motor, a blow-off valve which when openprevents the load on the compressor from falling below a predetermined amount, and

a connection between the regulating mechanism and the valve which opensthe latter when the amount of energy admitted to the motor by the regulator has been reduced to a predetermined value.

7. In combination, a centrifugal compressor which is subject to surging at light loads,

inlet and discharge conduits therefor, a

blow-ofl? valve in the discharge conduit which when open prevents the load 011 the compressor from falling below a predetermined amount, a driving motor, a regulator for the motor, an actuator forthe regu lator, a means moved by the actuator, and astem for the valve that is actuated by said means througha lost motion connection.

8. In combination, a centrifugal compressor having inlet and discharge conduits, a valve in one of the conduits, a motor for driving the compressor, a regulator for the motor, means for actuating the valve, means for actuating the regulator, a device which is situated between the said valve and regulator means for actuating both of them, and a lost motion connection included in one of the means.

In witness whereof, I have hereunto set my hand this 26th day of December, 1911.

RICHARD TROGER. I

Witnesses IRVING BONEPARTH,

I'IARRY F. PERISSI.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0. 

